Wednesday, 9 January 2013

Settings for recording a guitar performance

I just decided to write my current settings for recording a guitar performance in my Ubuntu Studio 12.10 distribution.

For capturing video I use a Live! Cam Chat HD de CreativeHD 720p which can manage 30 frames per second (this webcam comes with an incorporated microphone, so for simple tests, this is perfect and I can record both video/audio with vlc: open capture device (capture mode: Video for Linux 2, video device:  /dev/video0, audio: hw:1,0).

But most of the time I will want to get a different audio track, and then to post-process the video slightly. This is not very elegant but sort of works: I open Audacity and VLC at the same time. I start recording audio with Audacity (before opening the media capture with VLC, otherwise it gets stuck), then I start recording video with VLC. Once finished, I can apply one of the plugin effects in Audacity (most likely just a gentle reverb) and then export the Audacity audio to an MP3 file (the video captured with VLC goes by default to the Videos folder), and then I need to synchronize them.

To get the audio and video synchronized I use Kdenlive (0.9.2, and I set the default profile as Video4Linux). But I need to preprocess the video from my webcam, since it gets all broken when imported into Kdenlive. To get it right, when importing a new clip I first transcode it to HD720p 23.976fps (for 60 Mb/s). After this I get a .mov file, which can be loaded fine in Kdenlive.

Then I just load the .mp3 file from Audacity, the .mov file created above, and  I synchronize them (I do it manually with a visual cue, though Kdenlive has options for "Set audio reference", and "align with audio reference", which I should investigate). I apply basic effects fade-from-black, fade-to-black, fade-in, and fade-out, and I also add a basic title (any odd picture serves as background image, and nice fonts are Coolvetica).

Then I just choose the option to render to MPEG-4, which does a good job, the file created is small, and there are no audio lag issues that I notice with either Movie Player, VLC or Xine.

The resulting .mp4 file can be uploaded to Vimeo, and the result is also fine, with no apparent big audio lag issues.

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